A note on the effects of forward and rear-facing orientations on movement of horses during transport.

Several studies have attempted to determine the effects of orientation on a horse's ability to maintain balance during transportation. The results have often been contradictory because of differences in trailer design and lack of simultaneous comparisons. In this study, three replications of two forward-facing and two rear-facing horses were transported at the same time over a standardized course to allow for simultaneous comparisons. Each animal's total forward and backward motion during transport was calculated to estimate the effect of orientation on the horses' ability to maintain balance. The course consisted of four laps around a 3.6-km rectangular course, each lap reversing direction, totaling 14.4km. To mimic realistic travel, the course had artificial bumps, three turns (90 degrees, 45 degrees, and 135 degrees ), five straight-aways, and a hard stop at the end of each lap. Four horses were transported over the course in 3.7mx2.4m stalls mounted in-line on a 16-m long commercial straight-deck trailer (16 wheels). At the end of the first run (four laps), the orientation of each horse, two forward and two rear-facing, was reversed for a second run. Twelve horses were transported in each of the two orientations. Movement was recorded using video cameras positioned perpendicular to the horse's side. Movement while forward-facing ranged from 4.75 to 34.48m, averaging 12.95m; when rear-facing, movement ranged from 8.13 to 35.21m, averaging 16.99m, and was not statistically influenced by orientation (P=0.1219) due to high variation. Certain horses did demonstrate a superior ability to maintain balance in a particular orientation. Thus individual characteristics and other factors may play a larger role than orientation alone in the ability of horses to maintain balance during transport.